1. Technical Field
Aspects of the disclosure are generally directed to compositions comprising noble metal plasmonic nanoparticles (those that have characteristic strong surface plasmon resonance absorption and scattering shape tunable spectra) and methods of their use, for example, in the detection and treatment or prophylaxis of hyperproliferative conditions such as cancer.
2. Related Art
The increasing availability of nanostructures with highly controlled optical properties in the nanometer size range has created widespread interest in their use in biotechnological systems for diagnostic application and biological imaging. Cellular imaging utilizing microscope techniques provides anatomic details of cells and tissue architecture important for cancer diagnostics and research. Currently used optical probes include chemiluminescent, fluorimetric and colorimetric techniques. Markers attached to antibodies provide specific information about the presence of specific molecules. Quantum dots are widely used and studied for this application due to their unique size dependent fluorescence properties. But the potential human toxicity and cytotoxicity of the semiconductor material is one major problem for its in vivo application. Colloidal gold nanoparticles have become an alternative consideration due to their easy preparation, ready bioconjugation and potential noncytotoxicity. Immuno-gold nanoparticles conjugated to antibodies have provided excellent detection qualities for cellular labeling using electron microscopy.
Nanoparticles have also been used in photodynamic therapy (PDT) for treating cancer in vivo. In deep tissue, light in the near infrared region is used because near infrared light has maximal penetration through tissue due to the low scattering and absorption of intrinsic chromophores in the tissue. PDT for the management of malignant tumors is gaining acceptance in Europe and United States for various malignancies as new generation of photosensitizers becomes available and technological improvement in the delivery of light occurs. Current PDT agents include molecules preferentially taken up by the tumor cells. Light delivered to a tumor site, in the red region (600-700 nm), photochemically produces singlet oxygen that chemically injures the cell. Photodynamic therapy is distinguishable from photothermal therapy. Photothermal therapy uses heat instead of chemicals to treat cancer and other diseases. However, these agents are only relatively selective and risk of severe burns over the patient's entire body when exposed to light persists for 1 to 30 days depending on the agent used. Further, consistent light penetration in a tumor can be problematic indicating the need for even better photosensitizers and delivery sources.
Other thermal therapies for cancer have been widely investigated as a minimally invasive alternative to conventional surgical treatment. These cause necrosis of the cells through lysis and rupture of membranes and release of digestive enzymes; or denaturation of proteins, ribonucleic acids or deoxyribonucleic acids. A variety of heat sources have been employed such as microwaves, ultrasound and high power laser light as in photothermal therapy. They all have a common limitation that the heating is excessive and nonspecific and destroys both the malignant and benign cells.
Nanoshells composed of a dielectric silica core surrounded by a thin gold shell have been used as photothermal agents due to their wavelength selectivity, strong near infrared absorption efficiency and photo-stability. Nanoshells are disclosed in U.S. Pat. No. 6,530,944 The '944 patent discloses that a serious practical limitation to realizing many applications of solid metal nanoparticles is the inability to position the plasmon resonance at technologically important wavelengths, i.e., near infrared wavelengths. The '944 patent her teaches that solid gold nanoparticles of 10 nm in diameter have a plasmon resonance centered at 520 nm, and that this plasmon resonance cannot be controllably shifted by more than approximately 30 nanometers by varying the particle diameter or the specific embedding medium.
Thus, there is need for compositions and methods useful for detecting or treating pathologies such as cancer.